DETROIT — The United Auto Workers is expanding strikes to 38 parts and distribution locations across 20 states, targeting General Motors and Stellantis, UAW President Shawn Fain said Friday morning.

The union will not initiate additional strikes at Ford Motor, as the company has proven it’s “serious about reaching a deal,” Fain said in a Facebook Live comment.

“We still have serious issues to work through, but we do want to recognize that Ford is showing that they’re serious about reaching a deal,” said the outspoken union leader. “At GM and Stellantis, it’s a different story.”

Fain said the union and Ford have made progress on issues including eliminating some wage tiers, reinstating cost-of-living adjustments and an improved profit-sharing formula.

He also said the union won the right to strike over plant closures during the term of the deal as well as an immediate conversion of temporary, or supplemental, workers — those with at least 90 days of employment — upon ratification.

Ford said the company is “working diligently with the UAW to reach a deal,” but “we still have significant gaps to close on the key economic issues.”

“In the end, the issues are interconnected and must work within an overall agreement that supports our mutual success,” Ford said in a statement Friday.

The strikes at the GM and Stellantis parts suppliers will add roughly 5,600 autoworkers, including roughly 3,500 employees at GM, to the UAW’s ongoing strikes at the Detroit automakers.

“Today’s strike escalation by the UAW’s top leadership is unnecessary,” GM said in a statement. “We have now presented five separate economic proposals that are historic, addressing areas that our team members have said matters most: wage increases and job security while allowing GM to succeed and thrive into the future.

“We will continue to bargain in good faith with the union to reach an agreement as quickly as possible,” the automaker said.

Stellantis said in a statement it questions “whether the union’s leadership has ever had an interest in reaching an agreement in a timely manner.”

Roughly 12,700 UAW workers went on strike a week ago at the following locations: GM’s midsize truck and full-size van plant in Wentzville, Missouri; Ford’s Ranger midsize pickup and Bronco SUV plant in Wayne, Michigan; and Stellantis’ Jeep Wrangler and Gladiator plant in Toledo, Ohio.

Parts distribution centers have been a major point of concern during these talks, especially at Stellantis. The automaker has proposed consolidating 10 “Mopar” parts and distribution centers, which are scattered across the country, into larger Amazon-like distribution centers.

GM has agreed to eliminate the wage differences at its parts and components plants, according to Fain. He commended the Detroit automaker for that action but condemned it for resisting further measures that Ford has agreed to with the union.

Targeting the parts and distribution centers is a unique strategy. It does not affect the production and assembly of vehicles but rather the distribution of parts to dealers.

The new work stoppages, if prolonged, could cause significant disruption for dealers, which could in turn delay fixes for customers. Repair wait times have already been problematic due to recent supply chain issues.

“This will impact these two companies repairs operations,” Fain said. “Our message to the consumer is simple: The way to fix the frustrating customer experience is for the companies to end price gauging. Invest these record profits into stable jobs and stable wages and benefits.”

Many, including Wall Street analysts, expected the union to expand work stoppages to full-size truck plants of the Detroit automakers, which are crucial to the profitability of the companies.

The affected facilities for GM include 18 plants in 13 states: Michigan, Ohio, Colorado, Wisconsin, Illinois, Nevada, California, Texas, West Virginia, Mississippi, North Carolina, Tennessee and Pennsylvania.

For Stellantis, the extended strikes affect 20 facilities in 14 states: Michigan, Ohio, Wisconsin, Minnesota, Colorado, Illinois, California, Oregon, Georgia, Virginia, Florida, Texas, New York and Massachusetts.

“This expansion will also take our fight nationwide,” Fain said. “We will keep going, keep organizing and keep expanding the stand-up strike as necessary.”

UAW began targeted strikes after the sides failed to reach tentative agreements by the expiration of the previous contracts at 11:59 p.m. Sept. 14.

The additional plant strikes come despite record contract offers from the automakers, including roughly 20% hourly wage increases, thousands of dollars in bonuses, retention of the union’s platinum health care and other sweetened benefits.

Stellantis said on Friday it had made a “very competitive offer” that would see current full-time hourly employees earning between $80,000 and $96,000 a year by the end of the contract, constituting a 21.4% compounded increase; a long-term solution for an idled factory in Belvidere, Illinois; and, “significant product allocation that allows for workforce stability through the end of the contract.”

“We still have not received a response to that offer,” the company said.

The union has demanded 40% hourly pay increases, a shortened workweek, a shift back to traditional pensions, the elimination of compensation tiers and a restoration of cost-of-living adjustments, among other improvements.

The additional strikes come a day after The Detroit News Thursday night reported leaked messages involving UAW communications director Jonah Furman that raised questions about the union’s motives for the work stoppages.

In the undated private group messages, viewed by CNBC, Furman describes UAW’s strategy and targeted strikes as causing “recurring reputations damage and operational chaos.”

Furman, who did not respond for comment, said if the union “can keep them wounded for months they don’t know what to do.”

Fain did not address the messages on Facebook Live beyond discussing the union’s strategy of “doing things differently” to “win record contracts.”

— CNBC’s Gabriel Cortes and John Rosevear contributed to this report.